In a conventional thermal cutting machine, a workpiece mounted on a workpiece table has been cut by applying heat to the workpiece from the upper side of the workpiece. In order to prevent the workpiece table from being cut along with the workpiece, the workpiece has been supported from below by a workpiece table which is provided with a metallic frog having sharp distal ends (Japanese Unexamined Patent Application (A) 63-224893) or the workpiece has been supported by a workpiece table on which a metallic belt plate is longitudinally arranged (Japanese Published Examined Patent Application (B2) 3-31548).
However, in the former method, where the workpiece is supported by the workpiece table provided with the frog, there has been a disadvantage in that long-term use of the workpiece table causes the distal ends of the frog to wear, thereby enlarging the contact area with the workpiece and degrading the cutting quality of the product. Furthermore, if the product to be produced by the cutting operation is of small size, one side of the product would fall down between the projections of the frog so as to place the product in a tilted position which would interfere with the movement of the machining nozzle in an upright state, thereby damaging the machining nozzle.
In the latter method, where the metallic belt plate is longitudinally arranged on the workpiece table, the contact area of the workpiece table with the workpiece tends to be too large and degrades the cutting quality of the product. In addition, the belt plate must be replaced at frequent intervals because of it is easily damaged during the cutting operation of the workpiece. Further, since both cut products and scraps remain in a mixed state on the workpiece table, manual labor is required to classify them after the cutting operation.